Heat Transfer Efficiency For Boiling Water Increased 30 Fold

Jeez, here’s still another amazing innovation. Get this. A couple of researchers at Rensselaer Polytechnic Institute have figured out how to make water boil at a 30 fold increase in the number of bubbles created per unit of energy. That means that energy costs to create steam would drop by 30 fold. This process “could translate into considerable efficiency gains and cost savings if incorporated into a wide range of industrial equipment that relies on boiling to create heat or steam.”

Ya think one of them might be desalinaton? Hmm well also there is the Kanzius effect. An efficient heat transfer process there might make the 3000 degree flame net energy for the process. As well you might be able to get more steam for less energy to reduce costs of a kanzius steam reformation process. or efficiently boiled water might be injected into gypsum deposits. imho the salt would play hell on the nanorods that coat the copper sufaces mentioned in the article below. but if you could desalt and heat the water before it hit the nanorod copper plates the steam could be used to drive electrical generation more efficiently to reduce costs of membrane desalination. Finally, a word about pipelines. Maybe an efficient heat transfer material in combination with hydrophobic materials would enable cheaper ways to push water uphill in a pipe. Anyhow check out the article below. Interesting stuff. There’s a Rensselaer Polytechnic Institute Pr

As well as the write up below in PhyOrg.

Anyhow consider the article below.

New nano technique significantly boosts boiling efficiency

 A scanning electron microscope shows copper nanorods deposited on a copper substrate. Air trapped in the forest of nanorods helps to dramatically boost the creation of bubbles and the efficiency of boiling which in turn could lead to new ways of coo ...

A scanning electron microscope shows copper nanorods deposited on a copper substrate. Air trapped in the forest of nanorods helps to dramatically boost the creation of bubbles and the efficiency of boiling, which in turn could lead to new ways of cooling computer chips as well as cost savings for any number of industrial boiling application. Credit: Rensselaer Polytechnic Institute/ Koratkar

Whoever penned the old adage “a watched pot never boils” surely never tried to heat up water in a pot lined with copper nanorods.

A new study from researchers at Rensselaer Polytechnic Institute shows that by adding an invisible layer of the nanomaterials to the bottom of a metal vessel, an order of magnitude less energy is required to bring water to boil. This increase in efficiency could have a big impact on cooling computer chips, improving heat transfer systems, and reducing costs for industrial boiling applications.

“Like so many other nanotechnology and nanomaterials breakthroughs, our discovery was completely unexpected,” said Nikhil A. Koratkar, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer, who led the project. “The increased boiling efficiency seems to be the result of an interesting interplay between the nanoscale and microscale surfaces of the treated metal. The potential applications for this discovery are vast and exciting, and we’re eager to continue our investigations into this phenomenon.”

Bringing water to a boil, and the related phase change that transforms the liquid into vapor, requires an interface between the water and air. In the example of a pot of water, two such interfaces exist: at the top where the water meets air, and at the bottom where the water meets tiny pockets of air trapped in the microscale texture and imperfections on the surface of the pot. Even though most of the water inside of the pot has reached 100 degrees Celsius and is at boiling temperature, it cannot boil because it is surrounded by other water molecules and there is no interface — i.e., no air — present to facilitate a phase change.

Bubbles are typically formed when air is trapped inside a microscale cavity on the metal surface of a vessel, and vapor pressure forces the bubble to the top of the vessel. As this bubble nucleation takes place, water floods the microscale cavity, which in turn prevents any further nucleation from occurring at that specific site.

Koratkar and his team found that by depositing a layer of copper nanorods on the surface of a copper vessel, the nanoscale pockets of air trapped within the forest of nanorods “feed” nanobubbles into the microscale cavities of the vessel surface and help to prevent them from getting flooded with water. This synergistic coupling effect promotes robust boiling and stable bubble nucleation, with large numbers of tiny, frequently occurring bubbles.

“By themselves, the nanoscale and microscale textures are not able to facilitate good boiling, as the nanoscale pockets are simply too small and the microscale cavities are quickly flooded by water and therefore single-use,” Koratkar said. “But working together, the multiscale effect allows for significantly improved boiling. We observed a 30-fold increase in active bubble nucleation site density — a fancy term for the number of bubbles created — on the surface treated with copper nanotubes, over the nontreated surface.”

Boiling is ultimately a vehicle for heat transfer, in that it moves energy from a heat source to the bottom of a vessel and into the contained liquid, which then boils, and turns into vapor that eventually releases the heat into the atmosphere. This new discovery allows this process to become significantly more efficient, which could translate into considerable efficiency gains and cost savings if incorporated into a wide range of industrial equipment that relies on boiling to create heat or steam.

“If you can boil water using 30 times less energy, that’s 30 times less energy you have to pay for,” he said.

The team’s discovery could also revolutionize the process of cooling computer chips. As the physical size of chips has shrunk significantly over the past two decades, it has become increasingly critical to develop ways to cool hot spots and transfer lingering heat away from the chip. This challenge has grown more prevalent in recent years, and threatens to bottleneck the semiconductor industry’s ability to develop smaller and more powerful chips.

Boiling is a potential heat transfer technique that can be used to cool chips, Koratkar said, so depositing copper nanorods onto the copper interconnects of chips could lead to new innovations in heat transfer and dissipation for semiconductors.

“Since computer interconnects are already made of copper, it should be easy and inexpensive to treat those components with a layer of copper nanorods,” Koratkar said, noting that his group plans to further pursue this possibility.

Source: Rensselaer Polytechnic Institute

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4 Comments on “Heat Transfer Efficiency For Boiling Water Increased 30 Fold”

  1. Don Nguyen Says:

    The nanorods help to speed up the transition from convection to turbulent heat transfer. Once turbulence HT is set up, does it still help to reduce energy by 30 folds? It is already a great invention if it can improve heat tranfer by 100%.

  2. nick2 Says:

    Good question. In fact, you’ve pushed me out of my depth of understanding. So allow me to run a question by you.

    If the same unit of energy can produce 30 fold more bubbles of the same size–why would you not have a 30 fold decrease in the amount of energy required to make the same amount of steam. (rather than say 100%)

  3. Adrian Akau Says:

    I think the real question to be answered is will this effect occur at high pressures. Just because there are 30x the number of bubbles does not mean that 30x the number of molecules of water have been converted into water vapor. If the bubbles have 1/30 the volume of the regular bubbles, then there may be improvement in heat transfer but not necessarily in boiling efficiency. It may still take the same number of calories or BTU’s for a change of state (liquid water to steam) at a given pressure.

    adrianakau@aol.com

  4. nick2 Says:

    you know in an earlier post entitled:

    Distillation Desalination Using Low Pressure.

    …I asked

    Will someone kindly do the math that shows the energy needed to raise the temperature of water to steam vs the energy needed to lower the pressure on water to near vacume state so that it flashes to steam. Email the formula to me at cakilmer at yahoo.com and I’ll post it.

    https://nick2.wordpress.com/2007/01/12/distillation-desalination-using-low-pressure

    I think the question is…does the energy to lower pressure above water/water boiling unit volume a = energy to heat water/water boiling unit volume a

    if not what is the ratio

    no one ever emailed the formula. might be appropriate here.


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